Source:

Response:

The comets that entered the inner solar system a very long time ago
indeed have evaporated. However, new comets enter the inner solar
system from time to time. The Oort Cloud and Kuiper Belt hold many
comets deep in space, beyond the orbit of Neptune, where they do not
evaporate. Occasionally, gravitational perturbations from other comets
bump one of them into a highly elliptical orbit, which causes it to
near the sun.